In Japan of the Tokugawa Ieyasu period, a young ninja named Genbu wantonly kills samurai and other government officials, leaving his clan to face the blame.
That man, Fukusa, leads a peaceful life as a mirror maker under the name of Uncle Fu.
He has a young protégé, Sun Jing, a smug martial artist who constantly tries to prove himself by taking up every opportunity to fight.
When he sees his surrogate father attacked, Jing immediately rushes to his aid, but after several clashes he finds out that he and the ninja are evenly matched.
It is revealed that Genbu's father was not killed by his clan members; he instead died as a hero in a rebellion years ago.